There are no easy quick fixes and i'd be wary of experimenting on such a massive scale. It's like the other method, blocking sunlight to the planet, sounds like a great idea until everything reliant on photosynthesis starts dying off.
Most of the legitimate "block sunlight" proposals involve cloud seeding or spreading long-lasting particulates high in the upper atmosphere. The goal of these projects is to reflect 1-2% of sunlight, which would significantly cool the climate, but plants would hardly notice. In fact, organisms like reef systems would greatly appreciate it, as they're dying off at an extraordinary rate.
The forest are also dying from being too hot and dry. Any respite from the insane heat of summer would be well received. It's so much harder than it was 20 years ago!